WEB In-situ XRD annealing experiment to determine temperature stability of a 1D tungsten - hafnia selective emitters
Radiant thermal energy can be directly converted into electrical energy using a Thermophotovoltaic system (TPV). A selective emitter emits infrared radiation that matches the band gap of the photovoltaic cell used. The overall efficiency of the TPV system depends directly on the thermal stability of the selective emitter used in the system. In our work, we perform a detailed study to analyse the changes that take place in a 1D selective emitter containing alternate layers of metal and dielectric materials. The materials used in our selective emitter are tungsten/hafnia, and they are prepared by magnetron sputtering. In-situ XRD annealing experiments are carried out at temperatures above 800 °C and in a vacuum below 1 × 10-5 mbar vacuum at different time periods to validated the temperature stability of the emitter. We report on the structural and morphological changes individually in both the tungsten and hafnia layers and highlight the mechanisms that are responsible for the failure of the selective emitters at high temperatures.